The present invention relates to a compressor of the scroll type and more particularly to the constitution of the suction gas passage in a compressor of the scroll type.
It is well known that compressors of the scroll type have been used as compressors for compressing air, refrigerant, etc. FIGS. 1A to D of the attached drawings indicate fundamental constitutional elenents as well as the mode of operation of a compressor of this type. In the drawings the reference numeral 1 designates a stationary scroll, reference numeral 2 designates a movable scroll, reference numeral 3 designates a discharge port, and reference numeral 4 designates compressing chambers, and reference numeral 0 designates a definite point on stationary scroll 1 and reference numeral 0' designates a definite point on movable scroll 2, whereby in the drawings point 0 is adapted at the center of stationary scroll 1 and point 0' is at a point on a locus along which movable scroll 2 revolves around the center 0. Stationary and movable scrolls 1 and 2 each have a convolute shape of the same configuration which, as is well known in the art, may be involuted, or a combination of circular arcs, or the like although in the drawings it is assumed to be the involuted.
The operation of the compressor having the above constitution and as per se well known in the art is as follows.
In FIGS. 1A to D stationary scroll 1 is stationary relative to a point in space, and movable scroll 2 carries out a revolutional motion about a definite point 0 (the center of stationary scroll 1) without its attitude relative to the point in space being altered and maintaining contact of its convoluted walls with that of stationary scroll 1 as shown in the drawings. Thus, movable scroll 2 carries out the revolutional movement sequentially as shown in FIGS. 1A through D, designated 0.degree., 90.degree., 180.degree. and 270.degree., respectively. Owing to the revolutional motion of movable scroll 2, compression chambers 4 each having the shape of substantially a crescent formed between the convolutions constituting stationary and movable scrolls 1 and 2, respectively, gradually decrease the volumes so that the gases taken into compression chambers 4 are continuously and sequentially compressed and discharged from discharge port 3. During this processes the distance between points 0 and 0' shown in FIGS. 1A to D is maintained constant, the distance 00' being formulated as EQU 00'=(a/2)-t,
wherein a is a distance between the convolutions and t is the thickness of the convoluted scroll walls, a corresponding to the pitch of the convolution.
Next, FIG. 2 shows an example of a conventional compressor of the scroll type in a cross-sectional representation in which is mounted the scrolls 1 and 2 shown in FIG. 1 as the main components. In FIG. 2 are shown the stationary scroll 1, the movable scroll 2, a vertical crankshaft 3, compression chambers 4, a frame 5 in which scrolls 1, 2 are mounted, an Oldham's coupling 6 to subject movable scroll 2 to a revolutional motion, motor rotor 7 securing crankshaft 3, a motor stator 8, a first balancer 9, a second balancer 10, the balancers 9 and 10 being secured to rotor 7, a shell 11 hermetically enclosing the above elements, a suction pipe 12 opened in the lower part of shell 11, a discharge pipe 13 connected to stationary scroll 1, an air gap 14 formed between rotor 7 and stator 8, suction passages 15 formed in frame 5, and an oil sump 16 at the bottom of shell 11.
Movable scroll 2 is fit within stationary scroll 1, the former being connected to crankshaft 3 which is fit in frame 5, frame 5 and stationary scroll 1 being fastened together by bolts or the like (not shown), and Oldham's coupling 6 is positioned between movable scroll 2 and frame 5. Motor rotor 7 is connected to crankshaft 3 through a press fit or the like, and first and second balancers 9 and 10 are secured to motor rotor 7 at the upper and lower ends, respectively, by screws or the like (not shown). Frame 5 and motor stator 8 are fixedly secured to shell 11 through a press fit or the like.
The operation of this compressor, which is well known per se in the art, is as follows.
Upon flowing an electric current through motor stator 8, rotational torque is generated in motor rotor 7 which rotates crankshaft 3. Therefore, although movable scroll 2 begins to rotate about stationary scroll 1, since its rotation is prevented by Oldham's coupling 6, movable scroll 2 revolves relative to stationary scroll 1 and they cooperate in compressing an operational fluid based on the compression principle as was described above in reference to FIGS. 1A to D, whereby movable scroll 2 performs an eccentric revolutional movement relative to stationary scroll 1, the static and dynamic balancing of movable scroll 2 being effected by first and second balancers 9 and 10.
Thus, when the compressor operates, the gas as the operational fluid is sucked from suction pipe 12 as shown by the solid arrows in FIG. 2, and after it is passed through flow passages such as air gap 14 formed between motor rotor 7 and motor stator 8, etc. and cools the motor, it is sucked into compression chambers 4 through suction passages 15 formed in frame 5 via a suction portion 4a of compression chambers 4, it being compressed there and discharged from discharge pipe 13.
As shown in FIG. 2 by the dotted arrows the lubricating oil is supplied to the relative shifting portions of a journal 2a formed between crankshaft 3 and movable scroll 2 and journals 3b and 3c formed between crankshaft 3 and frame 5, as well as to a thrust shifting portion 2b formed between movable scroll 2 and frame 5 by centrifugal force from oil sump 16 due to the fact that crankshaft 3 is formed with an axial eccentric passage 3a therethrough and the lower end thereof is dipped into the lubricating oil accumulated in oil sump 16, the lubricating oil leaked from the respective shifting portions is returned to oil sump 16 by gravity through air gap 14 between motor stator 8 and motor rotor 7.
In the conventional compressor of the scroll type having such a constitution as above described, the lubricant leaked from relative shifting portions 2a, 3b, 3c and 2b is sucked into compression chamber 4 along with the sucked gas without returning to the oil sump 16 and therefore discharge outside the compressor from discharge pipe 13. Therefore, the lubricant within oil sump 16 runs dry so that problems at shifting portions 2a, 3b, 3c and 2b due to seizure may occur. In order to prevent the loss of lubricant a costly oil separator is necessarily provided. Alternatively, if the suction gas is adapted to be sucked directly into compression chambers 4, without passing through air gap 14 the lubricant may be prevented from being sucked together with the gas, but this brings about another difficulty in that the motor cannot be cooled by the sucked gas.